1. Field of the Invention
The present invention relates to a multiband antenna, particularly to a radiation conductor structure, wherein the high-frequency fed-in signal is directly coupled to the short-circuit member.
2. Description of the Related Art
Wireless communication products have been extensively popularized, and the related components are also growing more and more sophisticated. Particularly, the size and transmission performance of the antenna usually influence the sales volume of the product. How to integrate the transmission functions of multiple frequency bands into a limited accommodation space has become a critical technology for the manufacturers and researchers.
The conventional multiband antenna usually integrates at least two different antennae. A U.S. Pat. No. 6,204,819 disclosed a “Convertible Loop/Inverted-F Antennas and Wireless Communicators Incorporating the Same”, which is a dual-band antenna integrating an inverted-F antenna and a loop antenna, wherein a selecting switch feeds different signals into the two different antennae. However, the conventional dual-band antenna is a 3D structure bulky and hard to layout. Further, it needs a switching chip to operate band switching. Therefore, it has a complicated circuit structure and a higher the fabrication cost.
Another conventional multiband antenna technology, please refer to U.S. Pat. No. 7,372,406, disclosed a “Antenna Apparatus Including Inverted-F Antenna Having Variable Resonance Frequency”, which is an inverted-F antenna having at least two antenna conductive elements coupled in series via at least one switch and/or at least one resonant circuit, and whereby multiband antenna can provide tuning of a resonance frequency with a wider frequency range. However, such antenna structure is not only bulky but also complicate, and further it is challenging and complex to assemble the smaller mobile apparatus.
Another conventional technology use an antenna structure having complicated shapes and diversified dimensions to achieve a multiband function. However, the designers are usually beset by the complicated shapes and dimensions of this type of antennae because they are hard to layout in a wireless communication product.